JACKSON, Miss. (AP) — Vessels are moving cautiously through a section of the Mississippi River where a barge is leaking oil as the Coast Guard tries to ease the economic impact of shutting down one of the nation's vital commerce routes.

Chief Petty Officer Paul Roszkowski says officials are allowing northbound vessels to move through the area from sunset to sunrise and southbound vessels to continue their journeys in daylight hours.

Crews on Wednesday began pumping oil from the leaking barge onto another barge but Roszkowski said the transfer operation was halted at night because it's safer and easier to see if any oil is escaping during the day. Workers were to begin again Thursday morning.

Officials have not given estimates of how much oil has leaked from the barge, which struck a railroad bridge early Sunday.